Actuators for controlling multiple phase shifters of remote electronic downtilt base station antennas

ABSTRACT

Multi-RET actuators include a plurality of shafts that have respective axially-drivable members mounted thereon. Each of axially-drivable member is mechanically linked to a respective one of a plurality of phase shifters. The multi-RET actuator further includes a motor having a drive shaft and a gear system that is configured to selectively couple the motor to the respective shafts. The gear system is configured so that rotation of the drive shaft in a first direction creates a mechanical linkage between the motor and a first of the shafts  1340/1342 , and rotation of the drive shaft in a second direction that is opposite the first direction rotates the first of the shafts.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. § 119 to U.S.Provisional Patent Application Ser. No. 62/350,252, filed Jun. 15, 2016and U.S. Provisional Patent Application Ser. No. 62/370,065, filed Aug.2, 2016, and U.S. Provisional Patent Application Ser. No. 62/420,773,filed Nov. 11, 2016 the entire content of each of which is incorporatedherein by reference.

FIELD OF THE INVENTION

The present invention relates to communication systems and components,and in particular to actuators for electromechanical phase shifters usedin base station antennas.

BACKGROUND

Base station antennas for wireless communication systems are used totransmit radio frequency (“RF”) signals to, and receive RF signals from,cellular. Base station antennas are directional devices that canconcentrate the RF energy that is transmitted in certain directions (orreceived from those directions). The “gain” of a base station antenna ina given direction is a measure of the ability of the antenna toconcentrate the RF energy in that particular direction. The “radiationpattern” of a base station antenna is compilation of the gain of theantenna across all different directions. The radiation pattern of a basestation antenna is typically designed to service a pre-defined coveragearea, which refers to a geographic region in which mobile users cancommunicate with the cellular network through the base station antenna.The base station antenna may be designed to have minimum gain levelsthroughout this pre-defined coverage area, and it is typically desirablethat the base station antenna have much lower gain levels outside of thecoverage area. Early base station antennas typically had a fixedradiation pattern, meaning that once a base station antenna wasinstalled, its radiation pattern could not be changed unless atechnician physically reconfigured the antenna. Unfortunately, suchmanual reconfiguration of base station antennas after deployment, whichcould become necessary due to changed environmental conditions or theinstallation of additional base stations, was typically difficult,expensive and time-consuming.

More recently, base station antennas have been deployed that haveradiation patterns that can be reconfigured from a remote location. Forexample, base station antennas have been developed for which settingssuch as the down tilt angle, beam width and/or azimuth angle of theantenna can be reconfigured from a remote location by transmittingcontrol signals to the antenna. Base station antennas that can havetheir down tilt or “elevation” angle changed from a remote location aretypically referred to as remote electrical tilt (“RET”) antennas,although the term “RET antenna” is now also commonly used to coverantennas that can have their azimuth angle and/or beam width adjustedfrom a remote location. RET antennas allow wireless network operators toremotely adjust the radiation pattern of the antenna through the use ofelectro-mechanical actuators that may adjust phase shifters or otherdevices in the antenna to affect the radiation pattern of the antenna.Typically, the radiation pattern of a RET antenna is adjusted usingactuators that are controlled via control signal specificationspromulgated by the Antenna Interface Standards Group (“AISG”).

Base station antennas typically comprise a linear array or atwo-dimensional array of radiating elements such as dipole or crosseddipole radiating elements. In order to change the down tilt angle ofthese antennas, a phase taper may be applied across the radiatingelements, as is well understood by those of skill in the art. Such aphase taper may be applied by adjusting the settings on an adjustablephase shifter that is positioned along the RF transmission path betweena radio and the individual radiating elements of the base stationantenna. One known type of phase shifter is an electromechanical “wiper”phase shifter that includes a main printed circuit board and a “wiper”printed circuit board that may be rotated above the main printed circuitboard. Such wiper phase shifters typically divide an input RF signalthat is received at the main printed circuit board into a plurality ofsub-components, and then capacitively couple at least some of thesesub-components to the wiper printed circuit board. These sub-componentsof the RF signal may be capacitively coupled from the wiper printedcircuit board back to the main printed circuit board along a pluralityof arc-shaped traces, where each arc has a different diameter. Each endof each arc-shaped trace may be connected to a radiating element or to asub-group of radiating elements. By physically rotating the wiperprinted circuit board above the main printed circuit board, the locationwhere the sub-components of the RF signal capacitively couple back tothe main printed circuit board may be changed, which thus changes thepath lengths from the phase shifter to the radiating elements. Thischange in the path lengths results in a change in the phase of thesub-components of the RF signal, and since the arcs have differentradii, the change in phase experienced along each path differs.Typically, the phase taper is applied by applying positive phase shiftsof various magnitudes (e.g., +1°, +2° and +3°) to some of thesub-components of the RF signal and by applying negative phase shifts ofthe same magnitudes (e.g., −1°, −2° and −3°) to additional of thesub-components of the RF signal. Thus, the above-described wiper phaseshifters may be used to apply a phase taper to the sub-components of anRF signal that are applied to each radiating element (or sub-group ofradiating elements). Exemplary phase shifters of this variety arediscussed in U.S. Pat. No. 7,907,096 to Timofeev, the disclosure ofwhich is hereby incorporated herein in its entirety. The wiper printedcircuit board is typically moved using an electromechanical actuatorsuch as a DC motor that is connected to the wiper printed circuit boardvia a mechanical linkage. These actuators are often referred to as RETactuators since they are used to apply the remote electronic down tilt.

SUMMARY

Pursuant to embodiments of the present invention, an actuator for aplurality of phase shifters is provided that includes a plurality ofaxially-drivable members, each axially-drivable member mounted on arespective parallel shaft, the axially-drivable members configured to beconnected with a respective one of the phase shifters, a drive memberhaving a primary rotary member, and a plurality of secondary rotarymembers, each secondary rotary member mounted on a respective one of theparallel shafts. At least one of the primary rotary member and thesecondary rotary members are axially movable so that each secondaryrotary member may be in either an engaged position, in which thesecondary rotary member engages the drive member, and a disengagedposition, in which the secondary rotary member is disengaged from thedrive member. The actuator further includes a first engagement mechanismthat is configured to axially move the primary rotary member or one ofthe secondary rotary members so that at least one of the secondaryrotary members is in the engaged position and an electric motor that isconfigured to drive the drive member. The first engagement mechanism maycomprise an electromagnetic or a piezoelectric engagement mechanism.

In some embodiments, the first engagement mechanism is anelectromagnetic engagement mechanism that includes an electromagnet. Thefirst engagement mechanism may further include a permanent magnet or aferromagnetic structure that is axially aligned with the electromagnet.The first engagement mechanism may also include a spring that is betweenthe permanent magnet or ferromagnetic structure and the electromagnet.

In some embodiments, the first engagement mechanism is one of aplurality of engagement mechanisms, and each of the engagementmechanisms is configured to selectively move a respective one of thesecondary rotary members.

In some embodiments, the first engagement mechanism is configured tomove the primary rotary member to selectively engage the primary rotarymember with one of the secondary rotary members.

In some embodiments, the parallel shafts comprise worm gear shafts.

In some embodiments, the primary rotary member is a central gear andeach of the secondary rotary members are gears.

In some embodiments, the axially-drivable members comprise pistons.

In some embodiments, the spring biases one of the secondary rotarymember toward the disengaged position.

In some embodiments, the actuator may be part of a base station antennathat includes a plurality of linear arrays of radiating elements, whereeach of the phase shifters is coupled between the radiating elements ofa respective one of the linear arrays and a port of a radio.

Pursuant to further embodiments of the present invention, an actuatorfor a plurality of phase shifters is provided that includes a motor thatis configured to rotate a primary rotary member, a plurality ofaxially-drivable members, each axially-drivable member mounted on arespective shaft and configured to be connected with a respective one ofthe phase shifters, a plurality of secondary rotary members, eachsecondary rotary member mounted so that rotation thereof will result inrotation of a respective one of the shafts, and an electromagnet that isconfigured to move either the primary rotary member or a selected one ofthe secondary rotary members in response to a control signal so that theprimary rotary member engages the selected one of the secondary rotarymembers.

In some embodiments, the electromagnet is configured to move the primaryrotary member into engagement with the selected one of the secondaryrotary members.

In some embodiments, the actuator may further include a permanent magnetor a ferromagnetic structure that is axially aligned with theelectromagnet, where the electromagnet is attracted to the permanentmagnet or ferromagnetic structure in response to the control signal.

In some embodiments, the actuator may further include a spring that isbetween the permanent magnet or ferromagnetic structure and theelectromagnet, the spring biasing the primary rotary member into adisengaged position in which the primary rotary member is not engagedwith any of the secondary rotary members.

In some embodiments, the actuator may further include a permanent magnetthat is axially aligned with the electromagnet, where the electromagnetis repelled from the permanent magnet in response to the control signal.

In some embodiments, the actuator may further include a spring thatbiases the primary rotary member into a disengaged position in which theprimary rotary member is not engaged with any of the secondary rotarymembers, where the primary rotary member is between the spring and theelectromagnet.

In some embodiments, the spring may be a first spring, and the actuatormay further include a second spring and the primary rotary member may bebetween the first and second springs.

In some embodiments, the primary rotary member is mounted on a shaftthat is configured to be turned by the motor, and the primary rotarymember is mounted for axial movement along the shaft and to rotate inresponse to rotation of the shaft.

In some embodiments, the electromagnet is configured to move theselected one of the secondary rotary members into engagement with theprimary rotary member.

In some embodiments, the actuator may further include a permanent magnetor a ferromagnetic structure that is axially aligned with theelectromagnet, where the electromagnet is attracted to the permanentmagnet or ferromagnetic structure in response to the control signal.

In some embodiments, the actuator may further include a spring that isbetween the permanent magnet or ferromagnetic structure and theelectromagnet, the spring biasing the selected one of the secondaryrotary members into a disengaged position in which the primary rotarymember is not engaged with the selected on of the secondary rotarymembers.

In some embodiments, the actuator may further include a permanent magnetthat is axially aligned with the electromagnet, where the electromagnetis repelled from the permanent magnet in response to the control signal.

In some embodiments, the selected one of the secondary rotary membersincludes a rear portion having an internal cavity, the internal cavityreceiving an end of a respective one of the shafts when the selected oneof the secondary rotary members is engaged with the primary rotarymember.

In some embodiments, the electromagnet is one of a plurality ofelectromagnets and the control signal is one of a plurality of controlsignals, and each electromagnet is configured to move a respective oneof the secondary rotary members into engagement with the primary rotarymember in response to a respective one of the control signals.

In some embodiments, each of the shafts comprises a worm gear shaft, theprimary rotary member is a central gear and each of the secondary rotarymembers are gears.

Pursuant to still further embodiments of the present invention, anactuator for a plurality of phase shifters is provided that includes amotor that is configured to rotate a primary rotary member, a pluralityof axially-drivable members, each axially-drivable member mounted on arespective shaft, each axially-drivable member configured to beconnected with a respective one of the phase shifters, a plurality ofsecondary rotary members, each secondary rotary member mounted so thatrotation thereof will result in rotation of a respective one of theshafts, and a piezoelectric actuator that is configured to move aselected one of the secondary rotary members in response to a controlsignal to be rotatably engaged with the primary rotary member.

Pursuant to still further embodiments of the present invention, anactuator for a plurality of phase shifters is provided that includes aplurality of axially-drivable members, each axially-drivable membermounted on a respective parallel shaft, the axially-drivable membersconfigured to be connected with a respective one of the phase shifters,a central drive member, a plurality of rotary members, each mounted on arespective one of the parallel shafts, an engagement mechanism that isconfigured to rotate to selectively and exclusively engage each of theshafts to move a respective rotary member to the engaged position afirst drive unit to drive the central drive member, and a second driveunit configured to drive the engagement mechanism. Each of the rotarymembers is axially movable between an engaged position, in which therotary member engages the central drive member, and a disengagedposition, in which each rotary member is disengaged from the centraldrive member.

In some embodiments, the axially-drivable members comprise pistons.

In some embodiments, the parallel shafts comprise worm gear shafts.

In some embodiments, the parallel shafts include spring-loaded shaftsthat bias the rotary members toward the disengaged position.

In some embodiments, the engagement mechanism comprises a cam thatengages one of the parallel shafts to move a respective rotary memberattached to the shaft to the engaged position.

In some embodiments, the engagement mechanism includes a ring gear, andwherein the ring gear engages the second drive unit.

In some embodiments, the central drive member is a central drive gear.

In some embodiments, the rotary members are gears.

Pursuant to still further embodiments of the present invention, anactuator for a plurality of phase shifters is provided that includes aplurality of axially-drivable members, each axially-drivable membermounted on a respective parallel shaft, the axially-drivable membersconfigured to be connected with a respective one of the phase shifters,a central drive gear, a plurality of gears, each mounted on a respectiveone of the parallel shafts, an engagement mechanism that is configuredto rotate to selectively and exclusively engage each of the shafts tomove a respective gear to the engaged position in which the gear engagesthe central drive gear, a first drive unit to drive the central drivegear, and a second drive unit configured to drive the engagementmechanism.

In some embodiments, the axially-drivable members comprise pistonsand/or the parallel shafts comprise worm gear shafts.

In some embodiments, the parallel shafts include spring-loaded shaftsthat bias the gears toward the disengaged position.

In some embodiments, the engagement mechanism comprises a cam thatengages one of the parallel shafts to move a respective gear attached tothe shaft to the engaged position.

In some embodiments, the engagement mechanism includes a ring gear, andwherein the ring gear engages the second drive unit.

Pursuant to still further embodiments of the present invention, anactuator for a plurality of phase shifters is provided that includes aplurality of axially-drivable members, each axially-drivable membermounted on a respective parallel shaft, the axially-drivable membersconfigured to be connected with a respective one of the phase shifters,a central drive gear, a plurality of gears that are mounted onrespective ones of the parallel shafts and that are each axially movablebetween an engaged position, in which the gear engages the central drivegear, and a disengaged position, in which each gear is disengaged fromthe central drive gear, a cam plate with a cam that is configured torotate such that the cam selectively and exclusively engages each of theshafts to move a respective gear to the engaged position, a first driveunit to drive the central drive gear, and a second drive unit configuredto drive the cam plate.

In some embodiments, the axially-drivable members comprise pistonsand/or the parallel shafts comprise worm gear shafts.

In some embodiments, the parallel shafts include spring-loaded shaftsthat bias the gears toward the disengaged position.

In some embodiments, the cam plate includes a ring gear, and the ringgear engages the second drive unit.

Pursuant to still further embodiments of the present invention, anactuator for a plurality of phase shifters is provided that includes aplurality of shafts having respective axially-drivable members mountedthereon, each axially-drivable member configured to be connected with arespective one of the phase shifters, a motor having a drive shaft, anda gear system that is configured to selectively couple the motor to therespective shafts. The gear system is configured so that rotation of thedrive shaft in a first rotative direction creates a mechanical linkagebetween the motor and a first of the shafts, and rotation of the driveshaft in a second rotative direction that is opposite the first rotativedirection rotates the first of the shafts.

In some embodiments, the gear system includes a forward-directionprimary drive gear that is connected to the drive shaft and areverse-direction primary drive gear that is connected to the driveshaft

In some embodiments, the forward-direction primary drive gear and thereverse-direction primary drive gear are each ratcheted gears thatrotate in response to rotation of the drive shaft in the second rotativedirection and which do not rotate in response to rotation of the driveshaft in the first rotative direction.

In some embodiments, the actuator further includes a reversing gear thatis configured to engage the reverse-direction primary drive gear androtate in a direction opposite to the direction of rotation of thereverse-direction primary drive gear.

In some embodiments, the gear system further includes a plurality ofsecondary drive members mounted on respective ones of the shafts, eachsecondary drive member mounted so that rotation thereof will result inrotation of a respective one of the shafts.

In some embodiments, the gear system includes an engagement mechanismthat is configured to rotate to selectively and exclusively engage oneor more of the shafts to move a selected one of the secondary drivemembers into engagement with one of the forward-direction primary drivegear or the reversing gear.

In some embodiments, the engagement member comprises a rotating camplate.

Pursuant to still further embodiments of the present invention, a methodof adjusting a phase shifter is provided in which a drive shaft isrotated in a first rotative direction to connect a first of a pluralityof gears to a drive mechanism and then the drive shaft is rotated in asecond rotative direction to rotate the drive mechanism, where rotationof the drive mechanism causes rotation of the first of the plurality ofgears and rotation of the first of the plurality of gears mechanicallyadjusts a physical position of a component of the phase shifter.

In some embodiments, the plurality of gears comprises a plurality ofsecondary drive gears that are configured to rotate respective shafts,and the drive mechanism comprises a forward-direction primary drive gearthat is connected to the drive shaft and a reverse-direction primarydrive gear that is connected to the drive shaft.

In some embodiments, the forward-direction primary drive gear is aratcheted gear that only rotates in response to rotation of the driveshaft in a first rotative direction.

In some embodiments, the reverse-direction primary drive gear is aratcheted gear that only rotates in response to rotation of the driveshaft in the first rotative direction.

In some embodiments, rotating the drive shaft in the first rotativedirection to connect the first of the plurality of gears to the drivemechanism comprises using the rotating drive shaft to rotate a cam tomove the first of the plurality of gears into operative engagement withone of the forward-direction primary drive gear or the reverse-directionprimary drive gear.

In some embodiments, at least one of the forward-direction primary drivegear or the reverse-direction primary drive gear is configured to engagethe first of the plurality of gears through an intervening reversinggear.

Pursuant to still further embodiments of the present invention, anactuator for a plurality of phase shifters is provided that includes amotor that is configured to rotate a primary rotary member, a pluralityof axially-drivable members, each axially-drivable member mounted on arespective shaft, each axially-drivable member configured to beconnected with a respective one of the phase shifters, a plurality ofsecondary rotary members, each secondary rotary member mounted so thatrotation thereof will result in rotation of a respective one of theshafts, and a plurality of micro-motors, each micro-motor configured torotate a respective one of the shafts.

In some embodiments, the shafts comprise worm gear shafts.

In some embodiments, the primary rotary member is a central gear andeach of the secondary rotary members are gears.

In some embodiments, the axially-drivable members comprise pistons.

In some embodiments, the actuator further includes a plurality ofsprings that are mounted on the respective shafts, each springconfigured to bias a respective one of the secondary rotary membertoward a disengaged position where the secondary rotary member does notengage the primary drive member.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective view of a base station antenna that includes asingle motor multi-RET actuator according to embodiments of the presentinvention.

FIG. 1B is an end view of the base station antenna of FIG. 1A thatillustrates the input/output ports thereof.

FIG. 1C is a schematic plan view of the base station antenna of FIG. 1Athat illustrates the three linear arrays of radiating elements thereof.

FIG. 2 is a schematic block diagram illustrating the connections betweenvarious of the components of the base station antenna of FIG. 1.

FIG. 3 is a front perspective view of a pair of electromechanical phaseshifters that may be included in the base station antenna of FIG. 1.

FIG. 4A is a perspective view of a single motor multi-RET actuatorassembly according to embodiments of the present invention.

FIG. 4B is a front perspective view of the multi-RET actuator includedin the multi-RET actuator assembly of FIG. 4A with one of the baseplates removed therefrom.

FIG. 4C is a side perspective view of the multi-RET actuator of FIG. 4B.

FIG. 4D is a partial side perspective view of the multi-RET actuatorincluded in the assembly of FIG. 4A with one of the base plates and themotor removed that illustrates one of the secondary drive gears engagingthe primary drive gear of the actuator.

FIG. 4E is a partial side view of the multi-RET actuator of FIG. 4B thatillustrates one of the secondary drive gears engaging the primary drivegear of the actuator.

FIG. 5A is a schematic block diagram of a single motor multi-RETactuator according to further embodiments of the present invention.

FIGS. 5B and 5C are schematic block diagrams of a single motor multi-RETactuator according to still further embodiments of the present inventionthat illustrate a secondary drive gear thereof in its disengaged andengaged positions, respectively.

FIG. 5D is a schematic block diagram of a single motor multi-RETactuator according to yet additional embodiments of the presentinvention.

FIG. 5E is a schematic block diagram of a single motor multi-RETactuator according to yet further embodiments of the present invention.

FIG. 6 is a schematic block diagram of a single motor multi-RET actuatoraccording to embodiments of the present invention in which the primarydrive gear is moved as opposed to the secondary drive gears.

FIG. 7 is a schematic block diagram of a single motor multi-RET actuatoraccording to further embodiments of the present invention that has aprimary drive gear that can be moved in two different directions viaapplication of electromagnetic force.

FIG. 8 is a schematic block diagram of a single motor multi-RET actuatoraccording to further embodiments of the present invention that uses apiezoelectric actuator to connect a selected mechanical linkage to amotor.

FIG. 9A is a side view of a multi-RET actuator according to furtherembodiments of the present invention.

FIG. 9B is a partial side view of the multi-RET actuator of FIG. 9A withone of the secondary drive gears engaged with the primary drive gear.

FIG. 9C is a partial side sectional view of the multi-RET actuator ofFIG. 9A.

FIG. 9D is a partial side perspective view of the multi-RET actuator ofFIG. 9A with none of the secondary drive gears engaged with the primarydrive gear.

FIG. 9E is a partial side perspective view of the multi-RET actuator ofFIG. 9A with one of the secondary drive gears engaged with the primarydrive gear.

FIG. 10A is perspective view of a multi-RET actuator assembly accordingto further embodiments of the invention.

FIG. 10B is a perspective view of the multi-RET actuator of FIG. 10Awith the housing removed therefrom.

FIG. 10C is a perspective view of the actuator included in the multi-RETactuator assembly of FIGS. 10A-10B.

FIG. 10D is a perspective view of the actuator of FIG. 10C with themotors, cam plate and one base plate removed.

FIG. 10E is a side view of the actuator of FIG. 10C.

FIG. 10F is another perspective view of the actuator of FIG. 10C withthe motors, cam plate and one base plate removed.

FIG. 11A is a schematic front view illustrating operation of a multi-RETactuator according to still further embodiments of the presentinvention.

FIG. 11B is a schematic top view of a portion of the multi-RET actuatorof FIG. 11A.

FIG. 11C is conceptual diagram illustrating operation of the gearsattached to the drive shaft of the actuator of FIGS. 11A-11B.

DETAILED DESCRIPTION

Modern base station antennas often include two, three or more lineararrays of cross-polarized radiating elements. Thus, it is not uncommonfor a base station antenna to have eight, twelve or even more adjustablephase shifters for applying remote electronic down tilts to the lineararrays. Such a large number of phase shifters and associated RETactuators and mechanical linkages can significantly increase the size,weight and cost of the base station antenna.

Conventionally, a separate RET actuator has been provided for each phaseshifter (or pair of phase shifters if dual polarized radiating elementsare used in a linear array, as the same phase shift is typically appliedto each polarization). More recently, RET actuators have been proposedthat may be used to move the wiper printed circuit board on as many astwelve phase shifters. For example, U.S. Patent Publication No.2013/0307728 (“the '728 publication”) discloses a RET actuator that maybe used to drive six different mechanical linkages for purposes ofadjusting six different phase shifters using one multi-RET actuator.

Pursuant to embodiments of the present invention, fully automatedmulti-RET actuators are provided. The multi-RET actuators according toembodiments of the present invention may be controlled from a remotelocation to independently adjust the settings of one or more of aplurality of phase shifters. In some embodiments, the multi-RETactuators include two motors. In these embodiments, the first motor mayoperate to select one of a plurality of mechanical linkages that is tobe moved, and the second motor may be used to move the selectedmechanical linkage. In other embodiments, single motor multi-RETactuators are provided. In some of these single-motor embodiments, aratcheted gear system may be provided that allows the motor to bothselect the mechanical linkage that is to be moved and to then move theselected mechanical linkage. In other embodiments, a separate actuatorsystem such as, for example, remotely controlled electromagnets may beused to select the mechanical linkage that is to be moved, and thesingle motor may then be used to move the selected mechanical linkage.In still other embodiments, multi-RET actuators are provided that use amain drive motor and a plurality of micro-motors.

The multi-RET actuators according to embodiments of the presentinvention may be used to rotate a primary drive gear (or a pair ofprimary drive gears in one embodiment) that is mounted on the driveshaft of a motor. A plurality of worm gear shafts are provided, each ofwhich has a respective secondary drive gear associated therewith. Aselected one or more of the secondary drive gears may be moved to engagethe primary drive gear. Each secondary drive gear may be connected toits associated worm gear shaft so that rotation of the primary drivegear causes the selected secondary drive gear to rotate, which in turnimparts rotational movement to the worm gear shaft on which the selectedsecondary drive gear is mounted. Rotation of the worm gear shaft causesa piston mounted thereon to move along the longitudinal axis of its wormgear shaft. Each piston may be connected via a mechanical linkage to awiper arm on an adjustable phase shifter so that movement of the pistonmay be used to adjust the setting of the phase shifter.

In order to allow the adjustable phase shifters that are connected toeach respective mechanical linkage to be independently adjusted, themulti-RET actuators according to embodiments of the present inventioncan select which of the secondary drive gears contacts the primary drivegear so that movement of the primary drive gear results in correspondingrotation of only the selected secondary drive gear. In some embodiments,electromagnets may be used to move selected ones of the secondary drivegears into engagement with the primary drive gear in response to controlsignals from a remote location. In other embodiments, piezoelectricactuators may be used to move selected ones of the secondary drive gearsinto engagement with the primary drive gear. In still other embodiments,other electro-mechanical mechanisms may be provided that move selectedones of the secondary drive gears into engagement with the primary drivegear. In further embodiments, micro-motors may be used to move selectedones of the secondary drive gears into engagement with the primary drivegear. In still other embodiments, an indexing cam plate may be used tomove selected ones of the secondary drive gears into engagement with theprimary drive gear. Moreover, while the embodiments discussed belowprimarily (but not exclusively) discuss actuators in which the selectedsecondary drive gears are moved to engage the primary drive gear, itwill be appreciated that in other embodiments the primary drive gear maybe moved to engage one or more selected secondary drive gears.

Embodiments of the present invention will now be discussed in greaterdetail with reference to the drawings.

FIG. 1A is a perspective view of a RET base station antenna 100 that mayinclude any of the multi-RET actuators according to embodiments of thepresent invention that are disclosed herein. FIG. 1B is an end view ofthe base station antenna 100 that illustrates the input/output portsthereof. FIG. 1C is a schematic plan view of the base station antenna100 that illustrates the three linear arrays of radiating elementsthereof. FIG. 2 is a schematic block diagram illustrating variousinternal components of the RET antenna 100 and the connectionstherebetween. It should be noted that FIG. 2 does not show the actuallocation of the various elements on the antenna, but instead is drawn toshown the connections between the various elements with a minimal numberof connection lines crossing. It will also be appreciated that theconnection lines in FIG. 2 represent paths for electrical signals (e.g.,RF transmission lines).

Referring to FIGS. 1A-1C and 2, the RET antenna 100 includes, amongother things, input/output ports 110, a plurality of linear arrays 120of radiating elements 130, duplexers 140, phase shifters 150 and controlports 170. As shown in FIGS. 1C and 2, the antenna 100 includes a totalof three linear arrays 120 (labeled 120-1 through 120-3) that eachinclude five radiating elements 130. It will be appreciated, however,that the number of linear arrays 120 and the number of radiatingelements 130 included in each of the linear arrays 120 may be varied. Itwill also be appreciated that different linear arrays 120 may havedifferent numbers of radiating elements 130.

Referring to FIG. 2, the connections between the input/output ports 110,radiating elements 130, duplexers 140 and phase shifters 150 areschematically illustrated. Each set of an input port 110 and acorresponding output port 110, and their associated phase shifters 150and duplexers 140, may comprise a corporate feed network 160. A dashedbox is used to illustrate one such corporate feed network 160 in FIG. 2.Each corporate feed network 160 connects the radiating elements 130 ofone of the linear arrays 120 to a respective pair of input/output ports110.

As shown schematically in FIG. 2 by the “X” that is included in eachbox, the radiating elements 130 may be cross-polarized radiatingelements 130 such as +45°/−45° slant dipoles that may transmit andreceive RF signals at two orthogonal polarizations. Any otherappropriate radiating element 130 may be used including, for example,single dipole radiating elements or patch radiating elements (includingcross-polarized patch radiating elements). When cross-polarizedradiating elements 130 are used, two corporate feed networks 160 may beprovided per linear array 120, a first of which carries RF signalshaving the first polarization (e.g., +45°) between the radiatingelements 130 and a first pair of input/output ports 110 and the secondof which carries RF signals having the second polarization (e.g., −45°)between the radiating elements 130 and a second pair of input/outputports 110, as shown in FIG. 2.

As shown in FIG. 2, an input port of each transmit (“TX”) phase shifter150 may be connected to a respective one of the input ports 110. Eachinput port 110 may be connected to the transmit output port of a radio(not shown) such as a remote radio head. Each transmit phase shifter 150has five output ports that are connected to respective ones of theradiating elements 130 through respective duplexers 140. The transmitphase shifters 150 may divide an RF signal that is input to an inputport 110 into a plurality of sub-components and may effect a phase taperto the sub-components of the RF signal that are provided to theradiating elements 130. In a typical implementation, a linear phasetaper may be applied to the radiating elements 130. As an example, thefirst radiating element 130 in a linear array 120 may have a phase ofY°+2X°, the second radiating element 130 in the linear array 120 mayhave a phase of Y°+X°, the third radiating element 130 in the lineararray 120 may have a phase of Y°, the fourth radiating element 130 inthe linear array 120 may have a phase of Y°−X°, and the fifth radiatingelement 130 in the linear array 120 may have a phase of Y°−2X°, wherethe radiating elements 130 are arranged in numerical order.

Similarly, each receive (“RX”) phase shifter 150 may have five inputports that are connected to respective ones of the radiating elements130 through respective duplexers 140 and an output port that isconnected to one of the output ports 110, The output port 110 may beconnected to the receive port of a radio (not shown). The receive phaseshifters 150 may effect a phase taper to the RF signals that arereceived at the five radiating elements 130 of the linear array 120 andmay then combine those RF signals into a composite received RF signal.Typically, a linear phase taper may be applied to the radiating elementsas is discussed above with respect to the transmit phase shifters 150.

The duplexers 140 may be used to couple each radiating element 130 toboth a transmit phase shifter 150 and to a receive phase shifter 150. Asis well known to those of skill in the art, a duplexer is a three portdevice that (1) passes signals in a first frequency band (e.g., thetransmit band) through a first port while not passing signals in asecond band (e.g., a receive band), (2) passes signals in the secondfrequency band while not passing signals in the first frequency bandthrough a second port thereof and (3) passes signals in both the firstand second frequency bands through the third port thereof, which isoften referred to as the “common” port.

As can be seen from FIG. 2, a base station antenna 100 that includesthree linear arrays 120 of radiating elements 130 may include a total oftwelve phase shifters 150. While the two transmit phase shifters 150 foreach linear array 120 (i.e., one transmit phase shifter 150 for eachpolarization) may not need to be controlled independently (and the sameis true with respect to the two receive phase shifters 150 for eachlinear array 120), there still are six sets of two phase shifters 150that should be independently controllable. Accordingly, six RETactuators would conventionally be used in a base station antenna havingthe linear array arrangement of base station antenna 100.

The base station antenna 100 may include various other components suchas low noise amplifiers, one or more processors, etc. that are notpictured in FIGS. 1A-1C and 2.

Each phase shifter 150 shown in FIG. 2 may be implemented as a rotatingwiper phase shifter. The phase shifts imparted by the phase shifter 150to each sub-component of the RF signal may be controlled by a mechanicalpositioning system that physically changes the position of the rotatingwiper of each phase shifter 150, as will be explained with reference toFIG. 3.

Referring to FIG. 3, a dual rotating wiper phase shifter assembly 200 isillustrated that may be used to implement, for example, two of thetransmit phase shifters 150 of FIG. 2 (that are associated with the samelinear array 120) or two of the receive phase shifters 150 of FIG. 2(that, again, are associated with the same linear array 120). The dualrotating wiper phase shifter assembly 200 includes first and secondphase shifters 202, 202 a. In the description of FIG. 3 that follows itis assumed that the two phase shifters 202, 202 a are each transmitphase shifters that have one input and five outputs. It will beappreciated that if the phase shifters 202, 202 a are instead used asreceive phase shifters then the terminology changes, because when usedas receive phase shifters there will be five inputs and a single output.

As shown in FIG. 3, the dual phase shifter 200 includes first and secondmain (stationary) printed circuit boards 210, 210 a that are arrangedback-to-back as well as first and second rotatable wiper printed circuitboards 220, 220 a (wiper printed circuit board 220 a is barely visiblein the view of FIG. 3) that are rotatably mounted on the respective mainprinted circuit boards 210, 210 a. The wiper printed circuit boards 220,220 a may be pivotally mounted on the respective main printed circuitboards 210, 210 a via a pivot pin 222. The two rotatable wiper printedcircuit boards 220, 220 a may be joined together at their distal endsvia a bracket 224.

The position of each rotatable wiper printed circuit boards 220, 220 aabove its respective main printed circuit board 210, 210 a is controlledby the position of a linkage shaft 228, the end of which may constituteone end of a mechanical linkage 226. The other end of the mechanicallinkage 226 (not shown) may be coupled to a multi-RET actuator accordingto embodiments of the present invention, as will be discussed in furtherdetail below. A position sensor 250 may be provided on one of therotatable wiper printed circuit boards 220, 220 a to detect the positionof the rotatable wiper printed circuit boards 220, 220 a.

Each main printed circuit board 210, 210 a includes a plurality oftransmission line traces 212, 214. The transmission line traces 212, 214are generally arcuate. In some cases the arcuate transmission linetraces 212, 214 may be disposed in a serpentine pattern to achieve alonger effective length. In the example illustrated in FIG. 3, there aretwo arcuate transmission line traces 212, 214 per main printed circuitboard 210, 210 a (the traces on printed circuit board 210 a are notvisible in FIG. 3), with the first arcuate transmission line trace 212being disposed along an outer circumference of each printed circuitboard 210, 210 a, and the second arcuate transmission line trace 214being disposed on a shorter radius concentrically within the outertransmission line trace 212. A third transmission line trace 216 on eachmain printed circuit board 210, 210 a connects an input pad 230 on eachmain printed circuit board 210, 210 a to an output pad 240 that is notsubjected to an adjustable phase shift.

The main printed circuit board 210 includes one or more input traces 232leading from the input pad 230 near an edge of the main printed circuitboard 210 to the position where the pivot pin 222 is located. RF signalson the input trace 232 are coupled to the transmission line traces onthe wiper printed circuit board 220 (not visible in FIG. 3). The RFsignals are coupled from the transmission line traces on the wiperprinted circuit board 220 to the transmission line traces 212, 214 onthe main printed circuit board. Each end of each transmission line trace212, 214 may be coupled to a respective output pad 240. A coaxial cable260 or other RF transmission line component may be connected to inputpad 230 (a coaxial cable 260 a is also coupled to the correspondinginput pad on the main printed circuit board 210 a of phase shifter 202a). A respective coaxial cable 270 or other RF transmission linecomponent may be connected to each respective output pad 240 (coaxialcables 270 a may likewise be coupled to the corresponding output pads onthe main printed circuit board 210 a of phase shifter 202 a).Connections other than coaxial cables 260, 270 may be used in otherembodiments. For example, in other embodiments, the main printed circuitboard 210 may be coupled to stripline transmission lines on a panelwithout additional coaxial cabling. As the wiper printed circuit board220 moves, an electrical path length from the input pad 230 of phaseshifter 202 to each radiating element 130 served by the transmissionlines 212, 214 changes. For example, as the wiper printed circuit board220 moves to the left it shortens the electrical length of the path fromthe input pad 230 to the output pad 240 connected to the left side oftransmission line trace 212 (which connects to a first radiating element130), while the electrical length from the input pad 230 to the outputpad 240 connected to the right side of transmission line trace 212(which connects to a second radiating element) increases by acorresponding amount. These changes in path lengths result in phaseshifts to the signals received at the output pads 240 connected totransmission line trace 212 relative to, for example, the output pad 240connected to transmission line trace 216.

The second phase shifter 202 a may be identical to the first phaseshifter 202. As shown in FIG. 3, the rotating wiper printed circuitboard 220 a of phase shifter 202 a may be controlled by the same linkageshaft 228 as the rotating wiper printed circuit board 220 of phaseshifter 202. For example, if a linear array 120 includes dual polarizedradiating elements 130, typically the same phase shift will be appliedto the RF signals transmitted at each of the two orthogonalpolarizations. In this case, a single mechanical linkage 226 may be usedto control the positions of the wiper printed circuit boards 220, 220 aon both phase shifters 202, 202 a. In other cases, the wiper printedcircuit boards 220, 220 a of the two phase shifters 202, 202 a may beconnected to separate linkage shafts 228.

As noted above, various physical and/or electrical settings of a RETantenna such as antenna 100 including the elevation angle can becontrolled from a remote location by transmitting control signals to theantenna 100 that cause electromechanical actuators to adjust thesettings on the electro-mechanical phase shifters 150. Conventionally, aseparate actuator was provided for each phase shifter 150 (or for a pairof phase shifters 150 associated with cross-polarized radiating elements130). As discussed above, more recently multi-RET actuators have beensuggested that may be used to control a plurality of different phaseshifters. These multi-RET actuators use a first “drive” motor to drivethe mechanical linkages and a second “indexing” motor to selectivelyconnect one of the mechanical linkages to the first drive motor.

Pursuant to embodiments of the present invention, multi-RET actuatorassemblies are provided that include a single motor that actuatesmultiple mechanical linkages. By eliminating one of the two motors fromthe above-discussed multi-RET actuator, the size, cost and weight of themulti-RET actuator assembly may be significantly reduced. FIGS. 4A-4Eillustrate a single motor multi-RET actuator assembly 300 according toembodiments of the present invention. In particular, FIG. 4A is aperspective view of the single motor multi-RET actuator 30Q, FIGS. 4Band 4C are a front perspective view and a side view, respectively, ofthe single motor multi-RET actuator 300 with the housing removedtherefrom, and FIGS. 4D and 4E are partial perspective and side views ofthe single motor multi-RET actuator 300 with the housing removed thatillustrate how one of a plurality of secondary drive gears may beselectively connected to a primary drive gear.

As shown in FIG. 4A, the multi-RET actuator assembly 300 includes ahousing 310 having a pair of connectors 320 mounted on one end wall 312of the housing 310. The housing 310 may be formed of any appropriatematerial, such as a metal or polymeric material. The housing 310 may beomitted in some embodiments. The connectors 320 may be mounted on aprinted circuit board (not shown) in some embodiments. Each connector320 may extend through a respective aperture 314 in the end wall 312.The connectors 320 may connect to communications cables that may be usedto deliver control signals from a base station control system to themulti-RET actuator assembly 300.

Referring now to FIGS. 4B-4E, an actuator 330 is mounted within thehousing behind the end wall 312. The actuator 330 includes a pair ofcircular base plates 332, 334 that are mounted within the housing 310. Athird base plate 336 may be provided at the distal end of the actuator330. Six generally parallel worm gear shafts 340 are provided thatextend along respective axes R1-R6 between base plates 334 and 336 (seeFIG. 4D). Each worm gear shaft 340 includes a worm gear extension 342that extends through the base plate 334 so that each worm gear shaft 340is rotatably mounted in the base plate 334. The worm gear shafts 340 aredistributed generally circumferentially equidistant from each other. Theworm gear extensions 342 may be formed integrally with theircorresponding worm gear shafts 340. Respective secondary drive gears 344are axially aligned with the worm gear extensions 342. Each worm gearextension 342 may extend partially into an internal cavity 347 of itsrespective secondary drive gear 344. In some embodiments, each worm gearextension 342 may extend into the internal cavity 347 of its respectivesecondary drive gear 344 when the secondary drive gear 344 is in itsresting (disengaged) position. In other embodiments, the worm gearextension 342 may only extend into the internal cavity 347 of itsrespective secondary drive gear 344 when the secondary drive gear 344 isin its engaged position. Each internal cavity 347 extends deeper intothe secondary drive gear 344 than necessary to receive the worm gearextension 342 of its mating worm gear shaft 340, which allows eachsecondary drive gear 344 to move axially towards its respective wormgear shaft 340, in the manner discussed below. A rear portion 345 ofeach secondary drive gear 344 is mounted in a respective opening in thebase plate 332 so that each secondary drive gear 344 is held in place onthe worm gear extension 342 of its respective worm gear shaft 340.

A spring 346 is mounted on the worm gear extension 342 of each worm gearshaft 340 between the base plate 334 and the respective secondary drivegears 344. Each secondary drive gear 344 may move axially along itsrespective worm gear extension 342 between the base plates 332, 334relative to its associated worm gear shaft 340, and may also rotate inconcert with its associated worm gear shaft 340, at least when thesecondary drive gear 344 is in its engaged position. The springs 346bias the secondary drive gears 344 toward base plate 332 and away frombase plate 334, such that a gap exists between each secondary drive gear344 and the base plate 334. The spring loading of the secondary drivegears 344 by the springs 346 may assist in returning the secondary drivegears 344 to their resting (disengaged) positions after the secondarydrive gears 344 are moved into their engaged positions in the mannerdiscussed below.

A piston 350 is mounted on each worm gear shaft 340. Each piston 350 maybe connected to one end of a respective mechanical linkage (not shown).The mechanical linkage may prevent each piston 350 from rotating inresponse to rotation of its respective worm gear shaft 340. Each piston350 may be internally threaded to mate with the external threads on itscorresponding worm gear shaft 340. Each piston 350 may thus beconfigured to move axially relative to its associated worm gear shaft340 along its respective axis R1-R6 upon rotation of the worm gear shaft340. The far end of each mechanical linkage may be connected to a wiperarm of a phase shifter or a pair of phase shifters as is discussed abovewith reference to FIG. 3. Consequently, rotation of a worm gear shaft340 may result in axial movement of the piston 350 mounted thereon, andthis axial movement is transferred via the mechanical linkage 226 to aphase shifter in order to rotate a wiper arm of the phase shifter.

A motor 360 is mounted forward of the base plate 332. A drive shaft 362extends from the motor 360. The motor 360 may be used to turn the driveshaft 362 to rotate about an eccentric axis R7. A primary drive gear 364is mounted on the drive shaft 362 and may be formed integrally with thedrive shaft 362 in some embodiments. The primary drive gear 364 ispositioned in the center of a circle defined by the worm gear shafts340, and is axially offset along axis R7 from the secondary drive gears344 that are mounted on the respective worm gear extensions 342. As willbe discussed in detail below, one or more of the secondary drive gears344 may be moved axially to engage the primary drive gear 364, so thatrotation of the primary drive gear 364 causes each such engagedsecondary drive gear 344 to rotate, which in turn rotates the associatedworm gear shafts 340, thereby resulting in axial movement of the pistons350. Herein, when a particular secondary drive gear 344 is engaged withthe primary drive gear 364, the worm gear shaft 340 that the secondarydrive gear 344 that is associated therewith is said to be “selected.”The primary drive gear 364 may be rotated in a first direction (e.g.,clockwise) to move the pistons 350 on any selected worm gear shaft 340away from the motor 360, and may be rotated in a second direction (e.g.,counter-clockwise) to move the pistons 350 on any selected worm gearshaft 340 toward the motor 360. In this fashion, the rotational movementof the drive shaft 362 may be transformed into axial movement by one ormore of the pistons 350.

As is further shown in FIGS. 4B-4E a magnet 370 and an electromagnet 372may be mounted on (or adjacent) each worm gear extension 342, onopposite sides of the springs 346. An electromagnet refers to a magnetwhose strength may be adjusted by application of an electric controlsignal. The polarity of an electromagnet may be reversed by reversingthe polarity of the control signal. In an example embodiment, theelectromagnets 372 may be connected to the secondary drive gears 344 andthe magnets 370 may be connected to the base plate 334. An electriccontrol signal may be applied to a selected one of the electromagnets372 in response to a control signal in order to increase the strength ofthe “selected” electromagnet 372. As the magnetic strength is increased,the electromagnet 372 may be strongly attracted to its associated magnet370, thereby pulling the “selected” secondary drive gear 344 toward thebase plate 334 (and compressing the spring 346) so that the secondarydrive gear 344 engages the primary drive gear 364. The remainingsecondary drive gears 344 may remain in their “resting” (disengaged)positions and hence are spaced apart from the primary drive gear 364,and therefore are not in position to drive any of the worm gear shafts340.

As noted above, an internal cavity 347 is provided in the rear portion345 of each secondary drive gear 344. As the secondary drive gear 344moves axially toward the base plate 334 in response to the electromagnetforce, the worm gear extension 342 is received within this internalcavity 347. The cross-sectional shape of the internal cavity 347 may bethe same as the cross-sectional shape of the portion of the worm gearextension 342 that is received therein (with the cross-sectional area ofthe worm gear extension 342 being slightly smaller so that the worm gearextension 342 may be received within the internal cavity 347).Accordingly, rotation of the secondary drive gear 344 will result inrotation of the worm gear extension 342, which in turn causes rotationof the worm gear shaft 340.

FIGS. 4B and 4C illustrate the default position for the actuator 330where none of the secondary drive gears 344 are engaged with the primarydrive gear 364. FIGS. 4D and 4E illustrate the positions of the gearswhen one of the six secondary drive gears 344 is engaged with theprimary drive gear 364. Notably, since the electromagnets 372 can becontrolled independently, any number of the secondary drive gears 344may be engaged with the primary drive gear 364 at the same time. Thismay allow phase shifts to be implemented more quickly.

Upon receiving a signal from a controller that a phase shift in theantenna is desired, the motor 360 may be activated to rotate the primarydrive gear 364 about the axis R7. Rotation of the primary drive gear 364rotates the engaged secondary drive gear 344 about its respective axis(in the example of FIGS. 4D-4E, axis R6), which in turn rotates the wormgear shaft 340 associated with the secondary drive gear 344 about theaxis R6. Rotation of the worm gear shaft 340 drives the piston 350axially along its associated worm gear shaft 340 until the piston 350reaches a desired position, at which point the motor 360 deactivates.

Notably, the actuator assembly 300 is capable of adjusting up to sixphase shifters 150, which is a typical number for a base stationantenna, which often include two high band arrays and one low bandarray, with each array having a transmit phase shifter and a receivephase shifter for each of two polarizations, for a total of four phaseshifters per linear array or twelve phase shifters total. Since a singleRET actuator may control both polarizations, a total of six RETactuators are required for such an antenna.

It will be appreciated that numerous modifications may be made to theactuator assembly 300. For example, the one or more of the pistons 350may be replaced by another axially-drivable member. The primary drivegear 364 may be any type of central drive gear, or even another varietyof a central drive member, such as a wheel or disc that frictionallyengages the secondary drive gears 344. Similarly, the secondary drivegears 344 may be replaced with another rotary member, such as a wheel ordisc that engages the primary drive member 364. The number of worm gearshafts 340 (and associated structures) may be increased or decreasedfrom six as appropriate depending upon the number of phase shifters thatneed to be controlled. Numerous other modifications are possible.

FIGS. 5A-5E, 6 and 7 illustrate single motor multi-RET actuatorsaccording to further embodiments of the present invention.

FIG. 5A is a schematic block diagram of a portion of a single motormulti-RET actuator 400 that is similar to the single motor multi-RETactuator 330 that is discussed above with reference to FIGS. 4A-4E.However, in the multi-RET actuator 400, the positions of one or more ofthe electromagnets 372 and the permanent magnets 370 are reversed. Thisis shown schematically in FIG. 5A, which uses a block diagram format toillustrate the base plates 332, 334, the drive shaft 362 with theprimary drive gear 364 mounted thereon, one of the worm gear shafts 340with a secondary drive gear 344 mounted on the extension 342 thereof.Various other elements of the multi-RET actuator 400 are not depicted inFIG. 5A such as the other worm gears 340 and their associated secondarydrive gears 344 and springs 346, the motor 360, the pistons 350, etc. inorder to simplify the drawing. The multi-RET actuator 400 may move aselected one of the secondary drive gears 344 into an engagement withthe primary drive gear 364 by applying a control signal to theelectromagnet 372 that increases the magnetism of the electromagnet 372in order to attract the permanent magnet 370 toward the electromagnet372, thereby moving a selected one of the secondary drive gears 344 intoengagement with the primary drive gear 364.

It will also be appreciated that the electromagnet 372 may be configuredto repel the permanent magnet 370 by switching the polarity of thecontrol signal supplied to the electromagnet. When a repelling force isused as opposed to an attractive force, the configuration of theelectromagnet 372, the permanent magnet 370 and each secondary drivegear 344 may be changed. FIGS. 5B and 5C are schematic block diagrams ofa portion of a single motor multi-RET actuator 500 according to stillfurther embodiments of the present invention that illustrate how arepelling force may be used in other embodiments of the presentinvention.

As shown in FIG. 5B, the multi-RET actuator 500 may be similar to themulti-RET actuator 400, except that the electromagnet 372 and thepermanent magnet 370 are moved to the other side of the secondary drivegear 344. The permanent magnet 370 may be mounted on or otherwiseconnected to the secondary drive gear 344 so that axial movement of thepermanent magnet 370 results in axial movement of the secondary drivegear 344. The spring 346 may bias the permanent magnet 370 (and hencethe secondary drive gear 344) toward the electromagnet 372. As shown inFIG. 5B, in this position, the secondary drive gear 344 is disengagedfrom the primary drive gear 364. When a control signal is applied to theelectromagnet 372, a magnetism of the electromagnet 372 may be greatlyincreased. The electromagnet 372 is oriented so that the magnetic forcerepels the permanent magnet 370. This repulsive magnetic force mayexceed the counter-acting bias force applied by the spring 346, andhence, as shown in FIG. 5C, when the electromagnet 372 is activated bythe control signal, the secondary drive gear 344 is moved intoengagement with the primary drive gear 364 so that rotational movementof the primary drive gear 364 results in rotational movement of thesecondary drive gear 344 (and hence rotation of the worm gear shaft340).

FIG. 5D is a schematic block diagram of a single motor multi-RETactuator 600 that is very similar to the multi-RET actuator 500, withthe only difference being that the permanent magnet 370 has been movedto the other side of the secondary drive gear 344. The multi-RETactuator 600 may operate identically to the multi-RET actuator 500, butthis modified embodiment is depicted to make clear that the positions ofthe electromagnet 372 and/or the permanent magnet 370 may be changedwithout materially effecting operation of the device. It will also beappreciated that if the secondary drive gear 344 (or something attachedthereto) is formed of a ferromagnetic material, the permanent magnet 370may be omitted in any of the embodiments disclosed herein.Alternatively, the permanent magnets 370 in any of the embodimentsdisclosed herein may be replaced with a structure that is formed of orincludes a ferromagnetic material that is attracted (or repelled,depending upon the orientation) from the electromagnet 372 when theelectromagnet is activated. The ferromagnetic structure may have thesame shape as the permanent magnet 370 or may have a different shape.The use of such ferromagnetic materials may be advantageous in someembodiments as it may reduce or eliminate any crosstalk between magnetsthat are in close proximity to each other, and also will reduce thepossibility that other structures in the actuator are unintentionallymagnetized such as the lead screw.

FIG. 5E is a schematic block diagram of a single motor multi-RETactuator 700 that is very similar to the multi-RET actuator 600 of FIG.5D, with the only difference being that an additional electromagnet 372is provided adjacent the base plate 334. The two electromagnets 372 arelabelled 372-1 and 372-2 for ease of description of this embodiment. Theelectromagnet 372-1 may impart a repulsive force on the permanent magnet370 in response to a control signal, while the electromagnet 372-2 mayimpart an attractive force on the permanent magnet 370 so that the twoelectromagnets 372-1, 372-2 work together to overcome the bias force ofthe spring 346 that is mounted on the worm gear extension 342 in orderto move the secondary gear 344 into engagement with the primary drivegear 364.

In the above-described embodiments, electromagnets are provided that areused to selectively move one or more of the secondary drive gears 344into engagement with the primary drive gear 364. Pursuant to furtherembodiments of the present invention, the primary drive gear 364 mayinstead be moved into engagement with a selected one of the secondarydrive gears 344. FIG. 6 is a schematic block diagram of a single motormulti-RET actuator 800 according to embodiments of the present inventionin which the primary drive gear 364 is moved as opposed to the secondarydrive gears 344. To simplify the figure, only two of the worm gearshafts 340 and their associated extensions 342 and secondary drive gears344 are illustrated in FIG. 6. It will be appreciated, that more thantwo worm gear shafts 340 and their associated elements may be provided.As shown in FIG. 6, the two secondary drive gears 344 are axially offsetfrom each other so that when the primary drive gear 364 is engaged withone of the secondary drive gears 344 it is not engaged with the other ofthe secondary drive gears 344. If more than two secondary drive gears344 are provided, the additional secondary drive gears 344 may likewisebe axially offset from each of the other secondary drive gears 344.

As shown in FIG. 6, the electromagnet 372 is mounted on the primarydrive gear 364 while the permanent magnet 370 is mounted on or adjacentthe base plate 334. A control signal may be applied to the electromagnet372 to increase the magnetism thereof so that the electromagnet 372 isattracted to the permanent magnet 370, thereby pulling the electromagnet372 (and the primary drive gear 364) axially along the drive shaft 362.The drive shaft 362 may, for example, have a transverse cross-sectionthat is non-circular such as, for example, a square transversecross-section. This may allow the primary drive gear 364 to move axiallyalong the drive shaft 362 while also ensuring that rotation of the driveshaft 362 will result in rotation of the primary drive gear 364.Different control signals may be used depending upon which of thesecondary drive gears 344 is to be selected. For example, if the primarydrive gear 364 is to engage the secondary drive gear 344-1, then theelectromagnet 372 may be caused to exhibit a first level ofelectromagnetic force that is sufficient to move the primary drive gear364 to compress the spring 366 a first amount so that the primary drivegear 364 engages secondary drive gear 344-1. If the primary drive gear364 is to engage the secondary drive gear 344-2, then the electromagnet372 may be caused to exhibit a second, greater, level of electromagneticforce that is sufficient to move the primary drive gear 364 to compressthe spring 366 a second amount so that the primary drive gear 364engages secondary drive gear 344-2. The secondary drive gears 344 may beoffset by axial amounts that are sufficient so that variation in theattraction force between the electromagnet 372 and the permanent magnet370 and or variation in the bias force of the spring 366 that may occurover time due to aging of components or due to other magnetic, frictionor other forces is sufficient so that the primary drive gear 364 willalways engage the selected one of the secondary drive gears 344.

In the embodiment of FIG. 6, it may be necessary for the primary drivegear 364 to move a greater distance, particularly if the multi-RETactuator 800 includes a relatively large number of secondary drive gears344 (e.g., 6). This may require the use of a more powerful electromagnet372 and/or a more powerful permanent magnet 370. Additionally, thetechnique described above where two electromagnets 372 may also be used.It will also be appreciated that the positions of the electromagnets 372and the permanent magnets 370 may be varied in the manner discussedabove with reference to FIGS. 5A-5E in the embodiment of FIG. 6.

FIG. 7 is a schematic block diagram of a single motor multi-RET actuator900 according to further embodiments of the present invention that has aprimary drive gear 364 that may be moved in two different directionsalong the drive shaft 362 in order to reduce the amount ofelectromagnetic force that may be necessary in operation.

As shown in FIG. 7, the single motor multi-RET actuator 900 is similarto the single motor multi-RET actuator 800 of FIG. 6, except that themulti-RET actuator 900 includes an additional spring 366 (the twosprings are labeled 366-1 and 366-2 in FIG. 7), an additionalelectromagnet 372 (the two electromagnets are labeled 372-1 and 372-2 inFIG. 7) and an additional permanent magnet 370 (the two permanentmagnets are labeled 370-1 and 370-2 in FIG. 7). In FIG. 7, the multi-RETactuator is illustrated as including a total of six worm gear shafts 340and associated elements (e.g., secondary drive gears 344) to betterillustrate the operation thereof. Note that only four of the worm gearshafts 340 and worm gear extensions 342 are visible in FIG. 7 because ofthe side view, although the secondary drive gears 344 that areassociated with the hidden worm gear shafts 340 are visible. It will beappreciated that the multi-RET actuator 900 may include a differentnumber of worm gear shafts 340.

In its resting position, the primary drive gear 364 may be axiallylocated at approximately a midpoint between the base plates 332, 334. Asshown in FIG. 7, three of the secondary drive gears 344 are locatedaxially to the left of the midpoint, while the other of the secondarydrive gears 344 are located axially to the right of the midpoint. Aspring 366-1 is mounted on the drive shaft 362 to the right of themidpoint, and a spring 366-2 is located on the drive shaft 362 to theleft of the midpoint. The electromagnets 372-1, 372-2 are mounted on theprimary drive gear 364 while the permanent magnets 370-1, 370-2 aremounted at the far ends of the respective springs 366-1, 366-2 from theprimary drive gear 364.

If, for example, a phase shifter attached via a mechanical linkage to aworm gear shaft 340 associated with one of the secondary drive gears 344that is to the left of the midpoint needs adjustment, a controller (notshown) may send a control signal to the electromagnet 372-2 to increasethe attractive force between electromagnet 372-2 and permanent magnet370-2. As a result, the primary drive gear 364 may move to the left,compressing spring 366-2 to a degree, so that the primary drive gear 364engages the desired secondary drive gear 344. If instead a phase shifterattached via a mechanical linkage to the worm gear shaft 340 associatedwith one of the secondary drive gears 344 that are to the right of themidpoint needs adjustment, then electromagnet 372-1 may be supplied acontrol signal so that a magnetic force is generated that moves theprimary drive gear 364 to the right to engage the desired secondarydrive gear 344, which is the situation shown in FIG. 7. In each of theabove cases, both electromagnets 372-1 and 372-2 may be used to move theprimary drive gear 364 by controlling one of the electromagnets 372 togenerate an attractive magnetic force and the other to generate arepelling magnetic force in a manner similar to the discussion of theembodiment of FIG. 5E above.

While electromagnetic force provides one mechanism for moving theprimary drive gear 364 into engagement with a selected one of thesecondary drive gears 344, or vice versa, it will be appreciated thatembodiments of the present invention are not limited to the use of suchelectromagnetic forces. Instead, embodiments of the present inventionextend to any mechanical force that may be applied in response to acontrol signal. For example, FIG. 8 is a schematic block diagram of asingle motor multi-RET actuator 1000 according to still furtherembodiments of the present invention that uses a piezoelectric actuatorto connect a selected mechanical linkage to a motor.

As shown in FIG. 8, the multi-RET actuator 1000 may be similar to themulti-RET actuator 400 of FIG. 5A, except that the electromagnet 372 andpermanent magnet 370 are replaced with a piezoelectric actuator 380.Piezoelectric actuators are known in the art and use the piezoelectriceffect to effect a physical movement. The piezoelectric effect refers toan electric charge that may accumulate in certain solid materials suchas crystals in response to applied mechanical stress. The piezoelectriceffect is thus a linear electromechanical interaction between themechanical and the electrical state in crystalline materials. Thepiezoelectric effect is a reversible process in that materialsexhibiting the direct piezoelectric effect (the internal generation ofelectrical charge resulting from an applied mechanical force) alsoexhibit the reverse piezoelectric effect (the internal generation of amechanical strain resulting from an applied electrical field).Piezoelectric actuators apply an electrical field to generate amechanical strain.

A separate piezoelectric actuator 380 may be provided for each of thesecondary drive gears 344 and may be configured to move the respectivesecondary drive gears 344 into engagement with the primary drive gear364 in response to respective control signals. While only one embodimentof the present invention is illustrated in the figures that includes apiezoelectric actuator 380, it will be appreciated that theelectromagnets/permanent magnets 372/370 of each of the otherembodiments disclosed herein may be replaced with piezoelectricactuators to provide a plurality of additional embodiments.

Piezoelectric actuators tend to only provide a small amount of physical,mechanical movement (often referred to as “stroke”), which can be alimitation in some applications. For example, a typical piezoelectricmaterial may only provide 0.1% strain, meaning that a 1 meter piece ofpiezoelectric material may be required to obtain a stroke of 1 mm.Amplified piezoelectric actuators may be used to mitigate thislimitation in some embodiments.

It will be appreciated that numerous modifications may be made to theabove-described example embodiments without departing from the scope ofthe present invention. As one example, the above described embodimentsimplement the primary drive gear as a central gear and the secondarydrive gears as gears that circumferentially surround the central primarydrive gear. It will be appreciated that in other embodiments thesecondary drive gears may only partially circumferentially surround acentral primary drive gear, or that the drive gears may have a differentarrangement such as the secondary drive gears being linearly arranged.In such an embodiment the central drive gear could move to engage arespective one of the secondary drive gears or an intermediate gear thatis engaged with the primary drive gear could move to engage a selectedon of the secondary drive gears. Numerous other arrangements arepossible. In each case an electromagnetic engagement mechanism and/or apiezoelectric engagement mechanism may be used to move one or more ofthe gears so that the primary drive gear may rotate a selected one (ormore) of the secondary drive gears.

Pursuant to further embodiments of the present invention, multi-RETactuator assemblies are provided that include a main motor and aplurality of small “micro-motors” that are used together to, forexample, serially actuate multiple mechanical linkages. While thesemulti-RET assemblies increase the total number of motors used, the sixmicro-motors may be less expensive than a single conventional motor, andthe micro-motors may be highly reliable and hence may involve less riskof failure in the field as compared to some other options. FIGS. 9A-9Eillustrate a multi-RET actuator 1130 that may be used as part of such amulti-RET actuator assembly. While FIGS. 9A-9E only depict the multi-RETactuator 1130, it will be appreciated that the multi-RET actuator may beincorporated, for example, into the multi-RET actuator assembly 300 ofFIG. 4A in place of the multi-RET actuator 330.

Referring now to the figures, FIG. 9A is a side view of the multi-RETactuator 1130, FIG. 9B is an enlarged, partial side view of themulti-RET actuator 1130 with one of the secondary drive gears thereofengaged with the primary drive gear, FIG. 9C is a partial side sectionalview of the multi-RET actuator 1130, FIG. 9D is a partial sideperspective view of the multi-RET actuator 1130 with none of thesecondary drive gears engaged with the primary drive gear, and FIG. 9Eis a partial side perspective view of the multi-RET actuator 1130 withone of the secondary drive gears engaged with the primary drive gear.

Referring first to FIGS. 9A, 9C and 9D, the multi-RET actuator 1130includes a pair of circular base plates 1132, 1134 that may be mountedwithin a housing (not shown) of the multi-RET actuator assembly (e.g.,within housing 310 of multi-RET actuator assembly 300). A third baseplate 1136 is provided at the distal end of the actuator 1130. The baseplates 1132, 1134, 1136 may be identical to the base plates 332, 334,336 of multi-RET actuator 330 and hence further description thereof willbe omitted herein. Six generally parallel worm gear shafts 1140 areprovided that extend along respective generally parallel axes betweenbase plates 1134 and 1136. Each worm gear shaft 1140 includes a wormgear extension 1142 that is rotatably mounted in the base plate 1134. Asecondary drive gear 1144 is axially aligned with each worm gearextension 1142. As shown best in FIG. 9C, each worm gear extension 1142may extend partially into an internal cavity 1147 of its associatedsecondary drive gear 1144. Each internal cavity 1147 extends deeper intothe secondary drive gear 1144 than necessary to receive the worm gearextension 1142 of its mating worm gear shaft 1140, which allows eachsecondary drive gear 1144 to move axially towards its associated wormgear shaft 1140. A rod-like rear portion of each secondary drive gear1144 is mounted in a respective opening in the base plate 1132. A spring1146 is mounted on each worm gear extension 1142. Each secondary drivegear 1144 may move axially along its respective worm gear extension1142, and may also rotate in concert with its associated worm gear shaft1140 when the secondary drive gear 1144 is in its engaged position sothat it engages the primary drive gear 1164. The springs 1146 bias thesecondary drive gears 1144 toward base plate 1132. The worm gear shafts1140, worm gear extensions 1142, secondary drive gears 1144 and springs1146 may be identical to the corresponding worm gear shafts 340, wormgear extensions 342, secondary drive gears 344 and springs 346 ofmulti-RET actuator 330 and hence further description thereof will beomitted herein.

An internally threaded piston 1150 is mounted on each externallythreaded worm gear shaft 1140. Each piston 1150 may be connected to arespective mechanical linkage (not shown). When a selected one of theworm gear shafts 1140 is rotated, the mechanical linkage that isconnected to the piston 1150 that is mounted on the selected worm gearshaft 1140 prevents the piston 1150 from rotating. As the externallythreaded worm gear shaft 1140 rotates, the piston 1150 moves axiallyrelative to the worm gear shaft 1140 along the axis of rotation of theworm gear shaft 1140, which in turn imparts the same axial movement tothe mechanical linkage that is connected to the piston 1150. The far endof each mechanical linkage may be connected to a phase shifter or a pairof phase shifters such as the phase shifters of FIG. 3. Thus, rotationof a worm gear shaft 1140 may impart axial movement to the piston 1150and its associated mechanical linkage 226 that is used to rotate a wiperarm of a phase shifter.

A main motor 1160 is mounted forward of the base plate 1132. A driveshaft 1162 extends from the main motor 160. The main motor 1160 may beused to rotate the drive shaft 1162. A primary drive gear 1164 ismounted on the drive shaft 1162 and may be formed integrally with thedrive shaft 1162. The primary drive gear 1164 is positioned in thecenter of a circle defined by the worm gear shafts 1140, and is axiallyoffset from the secondary drive gears 1144. The secondary drive gears1144 may be moved axially to engage the primary drive gear 1164, so thatrotation of the primary drive gear 1164 rotates each engaged secondarydrive gear 1144, which in turn rotates the associated worm gear shafts1140, thereby resulting in axial movement of the pistons 1150.

As is further shown in FIGS. 9A, 9C and 9D a micro-motor 1170 is mountedon each of the secondary drive gears 1144 forwardly of base plate 1132.The micro-motors 1170 may be small and relatively inexpensive. Eachmicro-motor 1170 has an associated externally threaded drive shaft 1172that rotates when its associated micro-motor 1170 is activated. Thedrive shafts 1172 may be rotated clockwise or counter-clockwise by themicro-motors 1170. An internally threaded piston 1174 is mounted on eachexternally threaded drive shaft 1172. A rear end of each piston 1174 isattached to a front portion of a respective one of the secondary drivegears 1144. When one of the micro-motors 1170 rotates in, for example,the clockwise direction, the piston 1174 mounted thereon movesrearwardly along the axis of the drive shaft 1172. This can best be seenin FIG. 9C, where the piston 1174-1 is shown in its retracted positionwhile piston 1174-2 has been moved rearwardly into an extended positionby activation of micro-motor 1170-2. As piston 1174-2 moves rearwardly,it pushes secondary drive gear 1144-2 rearwardly as well, compressingthe spring 1146-2, so that the geared portion of secondary drive gear1144-2 engages the primary drive gear 1164. As the secondary drive gear1144-2 is pushed axially toward the base plate 1134 by the micro-motor1170-2, the worm gear extension 1142-2 is received within the internalcavity 1147 in secondary drive gear 1144-2. The remaining secondarydrive gears 1144 may remain in their “resting” (disengaged) positionsand hence are spaced apart from the primary drive gear 1164.

Upon receiving a signal from a controller that a phase shift in theantenna is desired, the motor 1160 may be activated to rotate theprimary drive gear 1164. Rotation of the primary drive gear 1164 rotatesthe engaged secondary drive gear 1144-2 about its respective axis. Thecross-sectional shape of the internal cavity 1147 may be the same as thecross-sectional shape of the portion of the worm gear extension 1142-2that is received therein so that rotation of the selected secondarydrive gear 1144-2 by the primary drive gear 1164 results in rotation ofthe worm gear extension 1142-2, which in turn causes rotation of theworm gear shaft 1140-2. Rotation of the worm gear shaft 1140-2 drivesthe piston 1150 mounted thereon axially until it reaches a desiredposition, at which point the motor 1160 is deactivated.

It should be noted that multiple of the secondary drive gears 1144 maybe moved into their engaged positions at the same time so that the maindrive gear 1164 may move multiple of the pistons 1150 simultaneously.This may allow phase shifts to be implemented more quickly.

FIGS. 9A and 9D illustrate the default position for the multi-RETactuator 1130 where none of the secondary drive gears 1144 are engagedwith the primary drive gear 1164. FIGS. 9B, 9C and 9E illustrate thepositions of the gears when one of the six secondary drive gears 1144 isengaged with the primary drive gear 1164.

It will be appreciated that numerous modifications may be made to themulti-RET actuator 1130, including the modifications discussed abovewith respect to multi-RET actuator 330.

Pursuant to yet additional embodiments of the present invention,multi-RET actuator assemblies are provided that use a drive motor and astepper motor to actuate multiple mechanical linkages. Examples of suchembodiments are depicted in FIGS. 10A-10F. In particular, FIG. 10A isperspective view of a multi-RET actuator assembly 1200 according tofurther embodiments of the invention. FIG. 10B is a perspective view ofthe multi-RET actuator 1200 with the housing removed therefrom. FIG. 10Cis a perspective view of a multi-RET actuator 1230 that is included inthe multi-RET actuator assembly 1200 of FIGS. 10A-10B. FIG. 10D is aperspective view of the multi-RET actuator 1230 with the motors, camplate and one base plate removed. FIG. 10E is a side view of themulti-RET actuator 1230. FIG. 10F is another perspective view of theactuator 1230 with the motors, cam plate and one base plate removed.

The multi-RET actuator assembly 1200 is shown in FIG. 10A. The actuatorassembly 1200 includes a housing 1210 with a pair of connectors 1220mounted on one end wall 1212 thereof and a multi-RET actuator 1230 ismounted within the housing 1210. The housing 1210 may be formed of anyappropriate material, such as a metal or polymeric material.

Referring to FIG. 10B, the connectors 1220 may be mounted on a printedcircuit board 1222 in some embodiments. The circuit board 1222 ismounted next to the end wall 1212 so that the connectors 1220 extendthrough the end wall 1212. The connectors 1220 may connect tocommunications cables that may be used to deliver control signals from abase station control system to the multi-RET actuator assembly 1200.

Referring now to FIGS. 10B-10F, the actuator 1230 includes a pair ofcircular base plates 1232, 1234 that are mounted within the housing1210. A third base plate 1236 may be provided at the distal end of theassembly 1200. Six generally parallel worm gear shafts 1240 are providedthat extend along respective axes between base plates 1234 and 1236. Theworm gear shafts 1240 are distributed generally circumferentiallyequidistant from each other.

Each worm gear shaft 1240 has a worm gear extension 1242 extending fromthe forward end thereof through base plate 1234. Each worm gearextension 1242 may be formed integrally with its corresponding worm gearshaft 1240. Each worm gear shaft 1240 and its corresponding worm gearextension 1242 are rotatably mounted in the base plate 1234. A selectorgear 1244 is mounted axially on each work gear extension 1242 so thateach worm gear extension extends axially into an internal cavity withinthe selector gear 1244. A spring 1246 is mounted on each worm gearextension between the base plate 1234 and the selector gear 1244. Eachspring 1246 biases its associated selector gear 1244 away from the baseplate 1234 and toward base plate 1232, such that a gap exists betweeneach selector gear 1244 and the base plate 1234. The spring loading ofthe selector gears 1244 by the springs 1246 may assist in returning theselector gears 1244 to their resting (disengaged) positions after theselector gears 1244 are moved into their engaged positions in the mannerdiscussed below

Each selector gear 1244 is mounted onto its respective worm gearextension 1242 so that the selector gear 1244 can move axially betweenthe base plates 1232, 1234 relative to the worm gear extension 1242. Theend of each worm gear extension 1242 may have a cross-section thatcorresponds to the cross-section of the internal cavity of itscorresponding selector gear 1244 so that rotation of the selector gear1244 causes corresponding rotation of the worm gear extension 1242 andthe worm gear shaft 1240 that the worm gear extension 1242 extends from.

A piston 1250 is mounted on each worm gear shaft 1240 and is configured(e.g., via threads) to move axially relative to the worm gear shaft 1240along its respective axis upon rotation of the worm gear shaft 1240.Each piston 1250 is connected to a mechanical linkage (not shown) thatassociates the piston 1250 with one or more phase shifters of anantenna, such that axial movement of the piston 1250 can cause at leastone phase shift in the antenna. For example, axial movement of thepiston 1250 can be used to move the wiper arm of the phase shifter 150of FIG. 3.

Referring now to FIGS. 10B-10D, a ringed cam plate 1270 is mountedforwardly and spaced apart from base plate 1232. The cam plate 1270 hasa nubbed cam 1272 that extends toward the base plate 1232. A ring gear1274 with teeth on its inner diameter extends axially from the cam plate1270 and is positioned for rotation about a central axis that extendsgenerally in parallel and in the center of the axes defined by the wormgear shafts 1240. A cam plate drive motor 1276 is eccentrically mountedto rotate about an eccentric axis R; a gear (not shown) on a shaft (notshown) attached to the cam plate drive motor 1276 engages the teeth ofthe ring gear 1274.

Referring again to FIGS. 10B-10F, a stepper gear motor 1260 is mountedcollinearly with the ring gear 1274 forward of the base plate 1232. Astepper gear 1264 is mounted to a drive shaft 1262 of the stepper gearmotor 1260 and is positioned adjacent the base plate 1232 for rotationabout the central axis. The stepper gear 1264 may be formed integrallywith the drive shaft 1262. The stepper gear 1264 is positioned in thecenter of a circle defined by the worm gear shafts 1240, and is axiallyoffset from the stepper gears 1244 that are mounted on the respectiveworm gear extensions 1242 when the stepper gears 1244 are in theirresting (disengaged) positions. The stepper gear 1264 is sized so thatits teeth can engage the teeth of a selector gear 1244 when the selectorgear 1244 is in position adjacent the base plate 1234.

In operation, the cam plate 1270 is rotated about the central axis to anorientation in which the cam 1272 is positioned between the forward endsof two the selector gears 1244. When the cam 1272 is in this position,all of the selector gears 1244 are positioned to be spaced from the baseplate 1234. Accordingly, all of the selector gears 1244 are disengagedfrom the stepper gear 1264, and therefore are not in position to driveany of the worm gear shafts 1240. As such, in this disengaged position,all of the pistons 1250 remain in place on their respective worm gearshafts 1240.

Upon a signal from a controller that a phase shift in the antenna isdesired, the cam plate drive motor 1276 is activated and begins torotate the cam plate 1270 about the central axis through interactionbetween the gear of the cam plate drive motor 1276 and the teeth of thering gear 1274. As the cam plate 1270 rotates about the central axis,the cam 1272 serially engages each of the forward ends of the steppergears 1244 and forces them toward the base plate 1234 and into positionfor engagement with the stepper gear 1264. Continued rotation of the camplate 1270 about the central axis moves the cam 1272 past the forwardend of a respective one of the selector gears 1244, allowing the springloading of the selector gear 1244 to return the selector gear 1244 toits rest position.

When the cam 1272 reaches the forward end of the selector gear 1244associated with the piston 1250 that is to be moved to induce the phaseshift in the antenna, the cam plate drive motor 1276 ceases to move,thereby allowing cam 1272 to remain in engagement with the forward endof the selector gear 1244. Engagement of the forward end of the selectorgear 1244 by the cam 1272 moves the selector gear 1244 rearwardly towardthe base plate 1234 and into engagement with the stepper gear 1264 (thisis shown in FIGS. 10D and 10F). The stepper gear motor 1260 thenactivates and rotates the stepper gear 1264 about the central axis.Rotation of the stepper gear 1264 rotates the engaged selector gear 1244about its respective axis, which in turn rotates the worm gear shaft1240 associated with the selector gear 1244 about the axis of the wormgear shaft 1240. Rotation of the worm gear shaft 1240 drives the piston1250 axially along the worm gear shaft 1240 until the piston 1250reaches a desired position, at which point the stepper gear motor 1260deactivates. The cam plate 1270 can either remain in position or move toa rest position to await the next phase shift instruction. The steppergear 1264 may be rotated in a first direction (e.g., clockwise) to movethe pistons 1250 on any selected worm gear shaft 1240 away from thestepper motor 1260, and may be rotated in a second direction (e.g.,counter-clockwise) to move the pistons 1250 on any selected worm gearshaft 1240 toward the stepper motor 1260.

The actuator 1230 is capable of adjusting up to six mechanical linkagesvia the six pistons 1250, each of which controls one or more phaseshifters. In other embodiments, more or fewer linkages may be included.

Those of skill in this art will recognize that other variations of theactuator 123Q may be employed. For example, the pistons 1250 may bereplaced by another axially-drivable member. The stepper gear 1264 maybe any type of central drive gear, or even another variety of a centraldrive member, such as a wheel or disc that frictionally engages theselector gears 1244. The selector gears 1244 may be replaced withanother rotary member, such as a wheel or disc that engages the centraldrive member. The cam plate 1270 and ring gear 1274 may be replaced withanother engagement mechanism that selectively and exclusively engagesone shaft at a time. The cam plate 1270 may have a recess rather than acam 1272, such that a respective selector gear 1244 moves toward thebase plate 1232 when the recess rotates in front of the selector gear,with engagement of the selector gear 1244 or other rotary member withthe stepper gear 1264 occurring at a position spaced apart from, ratherthan adjacent to, the base plate 1234. Drive units other than thestepper gear motor 1260 and the cam plate drive motor 1276 may beemployed. Other variations may also be apparent to those of skill inthis art.

Pursuant to still further embodiments of the present invention,multi-RET actuators are provided that use a single motor and aratchet-based gear system to actuate multiple mechanical linkages.Examples of such embodiments are depicted in FIGS. 11A-11C. Thesemulti-RET actuators may be similar to the single-motor multi-RETactuator 330 discussed above with reference to FIGS. 4A-4E, except theelectromagnetic system for moving the secondary drive gears included inthe multi-RET actuator 330 is replaced in multi-RET actuator 1330 with aratchet based gear system. The ratchet based gear system is similar tothe gear system included in the multi-RET actuator 1230 discussed above,but the use of ratcheted gears eliminates any need for a second motor.

Referring first to FIG. 11A, which is a schematic front view of themulti-RET actuator 1330 that illustrates various gears thereof, it canbe seen that the multi-RET actuator 1330 includes a plurality ofsecondary drive gears 1344, a forward-direction primary drive gear 1364,a reverse direction primary drive gear 1366 and a reversing gear 1368.The multi-RET actuator 1330 may include circular base plates, worm gearshafts, worm gear extensions, springs and pistons that may be identicalin both structure and arrangement to the base plates 1132, 1134, 1136,the worm gear shafts 1140, the worm gear extensions 1142, the springs1146 and the pistons 1150 of multi-RET actuator 1130, and hence furtherdescription thereof will be omitted herein.

FIG. 11B is a schematic top view of the various gears included inmulti-RET actuator 1330. A portion of one of the six worm gear shafts1340-1 and its associated worm gear extension 1342-1 and spring 1346-1are also illustrated in FIG. 11B, as is the circular base plate 1334that abuts the forward ends of the worm gear shafts 1340.

As shown in FIG. 11B, a drive shaft 1362 of the single motor (not shown)of multi-RET actuator 1330 has three gears mounted thereon, namely theforward-direction primary drive gear 1364, the reverse direction primarydrive gear 1366 and an indexing gear 1374. The forward-direction primarydrive gear 1364 and the reverse direction primary drive gear 1366 areeach ratcheted gears that only rotate in response to clockwise rotationof the drive shaft 1362 and which do not rotate in response tocounter-clockwise rotation of the drive shaft 1362. A ringed cam plate1370 is provided that may be located in the same position as the camplate 1270 of multi-RET actuator 1230, and which is similar in designthereto. The ringed cam plate 1370 includes a circular channel 1378 onthe rear surface thereof (shown in dotted lines in FIG. 11B whichillustrates what a cross-section of the cam plate 1370 would look like),although it will be appreciated that the channel 1378 may be omitted inother embodiments. The ringed cam plate 1370 includes a fixed cam plategear 1376 on a front surface thereof. The cam plate gear 1376 ispositioned such that it is permanently engaged with the indexing gear1374 that is mounted on drive shaft 1362. The cam plate 1370 furtherincludes a nubbed cam 1372 on its rear surface that extends toward thebase plate 1334. The cam 1372 is located in the channel 1378 so that thecam fills the channel 1378 and extends out of the channel 1378 as shownin FIG. 11B.

The cam plate 1370 is mounted for rotation about a central axis thereof(which may be the axis defined by the drive shaft 1362). The indexinggear 1374 is a ratchet gear that only rotates when the drive shaftrotates in a particular direction. For purposes of the discussionherein, it is assumed that the ratcheted indexing gear 1374 only rotateswhen the drive shaft rotates in the counter-clockwise direction, andthat the forward-direction primary drive gear 1364 and thereverse-direction primary drive gear 1366 only rotate when the driveshaft rotates in the clockwise direction. It will be appreciated,however, that these directions may be reversed in other embodiments.

When the motor 1360 (not shown) rotates the drive shaft 1362 in thecounter-clockwise direction, the indexing gear 1374 rotates in theclockwise direction. As noted above, a toothed cam plate gear 1376 isformed on the cam plate 1370. As the indexing gear 1374 is mounted sothat the teeth thereof are in permanent engagement with the teeth of camplate gear 1376, rotation of the indexing gear in the clockwisedirection causes counter-clockwise rotation of the cam plate 1370 (sincethe cam plate 1370 is fixed to the cam plate gear 1376). Thus, byrotating the drive shaft 1362 in the counter-clockwise direction it ispossible to rotate the cam plate 1370 in the counter-clockwisedirection. The nubbed cam 1372 on cam plate 1370 may then be used to“select” one of the secondary drive gears 1344 in the same manner thatthe nubbed cam 1272 may be used to select one of the secondary drivegears 1244 of multi-RET actuator 1230. Accordingly, further descriptionof the operation of cam plate 1370 and cam 1372 will be omitted.

As is also shown in FIG. 11B, the reversing gear 1368 is mounted forrotation on a shaft 1369 that extends rearwardly from the cam plate1370. The reversing gear 1368 is axially aligned with each secondarydrive gear 1344 and with the reverse-direction primary drive gear 1366(i.e., they are each at the same distance from the circular base plate1334). The reversing gear 1368 is positioned so that the teeth thereofpermanently engage the teeth of the reverse-direction primary drive gear1366, and so that the teeth of the reversing gear 1368 engage the teethof each secondary drive gear 1344 when the reverse-direction primarydrive gear 1366, the reversing gear 1368 and the secondary drive gear1344 at issue are radially aligned.

The multi-RET actuator 1330 may operate as follows. In order to move apiston (not shown) that is mounted on a first of the worm gear shafts1340-1 in a first direction (which we will assume here is the forwarddirection toward base plate 1334), the motor is activated to move thedrive shaft 1362 in the counter-clockwise direction. As discussed above,this causes the indexing gear 1374 to rotate in the counter-clockwisedirection which, via its interaction with the cam plate gear 1376,causes the cam plate 1370 to rotate in the counter-clockwise direction.The cam plate 1370 is rotated until the cam 1372 engages the forward endof secondary drive gear 1344-1 (i.e., the secondary drive gear that isassociated with the piston that is to be moved). As cam 1372 engagessecondary drive gear 1344-1, the secondary drive gear is pushedrearwardly so that the toothed section thereof engages for theforward-direction primary drive gear 1364. When this occurs, the motoris shut off. The cam plate 1370 may then be left in place or may berotated further. When the cam plate 1370 is further rotated, the cam1372 disengages from the selected secondary drive gear 1344, and thespring 1346 associated with the selected secondary drive gear 1344pushes the selected secondary drive gear 1344 back into its restingposition.

In order to move the piston in the forward direction, the motor isturned back on in the opposite direction so that the drive shaft 1362rotates in the clockwise direction. As discussed above, the indexinggear 1374 is ratcheted and hence does not rotate in response to theclockwise rotation of the drive shaft 1362. However, theforward-direction and reverse-direction primary drive gears 1364, 1366are oppositely ratcheted, and hence both of these gears 1364, 1366rotate in the clockwise direction in response to the clockwise rotationof the drive shaft 1362.

As the secondary drive gears 1344 are circumferentially spaced at equaldistances, the secondary drive gears 1344 may be radially spaced apartfrom each other at 60° intervals. As shown schematically in FIG. 11A,the reversing gear 1368 and the cam 1372 may be spaced apart from eachother by about 30°. As a result, when the cam 1372 is used to select oneof the secondary drive gears 1344 in the manner described above, thereversing gear 1368 may be radially positioned about midway between twoof the secondary drive gears 1344, and hence is not in contact with anyof the secondary drive gears 1344.

As the drive shaft 1362 rotates in the clockwise direction, both theforward-direction primary drive gear 1364 and the reverse-directionprimary drive gear 1366 rotate in the clockwise direction. Thereverse-direction primary drive gear 1366 rotates the reversing gear1368, but as the reversing gear 1368 does not engage any of thesecondary drive gears 1344, this rotation has no effect. The clockwiserotation of the forward-direction primary drive gear 1364 results incounter-clockwise rotation of the selected secondary drive gear 1344-1.The counter-clockwise rotation of the selected secondary drive gear1344-1 results in counter-clockwise rotation of the worm gear shaft1340-1, which causes the piston mounted thereon to move in the forwarddirection toward base plate 1334.

In order to move the piston associated with secondary drive gear 1344-1in the rearward direction (i.e., away from base plate 1334), the motoris activated to move the drive shaft 1362 in the counter-clockwisedirection. As discussed above, this causes the cam plate 1370 to rotatein the counter-clockwise direction. The cam plate 1370 is rotated untilthe reversing gear 1368 is radially aligned with the selected secondarydrive gear 1344-1 so that the teeth on the reversing gear 1368 engagethe teeth on the reverse-direction drive gear 1366 and the teeth of theselected secondary drive gear 1344-1. Note that when the cam plate 1370is rotated to this position, the cam 1372 is radially positioned betweentwo of the secondary drive gears 1344, and hence all six of thesecondary drive gears 1344 remain in their resting positions (i.e., theposition shown in FIG. 11B).

Once the reversing gear 1368 has been rotated to engage the selectedsecondary drive gear 1344-1, the motor reverses direction to rotate thedrive shaft 1362 in the clockwise direction. As the indexing gear 1374is ratcheted, it does not rotate in response to the clockwise rotationof the drive shaft 1362 and hence the cam plate 1370 remains stationary.The forward-direction and reverse-direction primary drive gears 1364,1366 rotate in the clockwise direction in response to the clockwiserotation of the drive shaft 1362.

As all of the secondary drive gears 1344 are in their respective restingpositions, the rotation of the forward-direction primary drive gear 1364does not have any effect. However, the clockwise rotation of thereverse-direction primary drive gear 1366 results in counter-clockwiserotation of the reversing gear 1368, which in turn results in clockwiserotation of the selected secondary drive gear 1344-1. The clockwiserotation of the selected secondary drive gear 1344-1 results inclockwise rotation of the worm gear shaft 1340-1, which causes thepiston mounted thereon to move in the rearward direction, away from baseplate 1334. Thus, as described above, the motor in conjunction with theratcheted gear system described above may be used to select any of theworm gear shafts 1340 and move a piston mounted thereon in eitherdirection.

FIG. 11C conceptually illustrates the operation of the drive shaft 1362and the ratcheted gears 1364, 1366, 1374 attached thereto. Note that toavoid undesired movements of non-selected ones of the secondary drivegears 1344 when the index gear 1374 is being moved, the torque of eachsecondary drive gear 1344 should be greater than the torque of thereversing gear 1368 plus the torque of the drive reverse-directionprimary drive gear 1366.

It should be noted that the forward-direction primary drive gear 1364and the reverse-direction primary drive gear 1366 need only move thepistons 1150 in opposite directions. The actual direction (i.e., forwardor reverse along the worm gear shafts 1140) of movement of the pistonsis arbitrary.

The multi-RET actuator 1330 of FIGS. 11A-11C may be viewed as comprisinga plurality of shafts (e.g., the worm gear shafts 1340 and theirassociated worm gear extensions 1342) that have respectiveaxially-drivable members (e.g., the pistons 1350) mounted thereon. Eachof axially-drivable member may be configured to be connected to arespective one of a plurality of phase shifters. The multi-RET actuator1330 further includes a motor 1360 having a drive shaft 1362 and a gearsystem that is configured to selectively couple the motor 1360 to therespective shafts 1340/1342. The gear system is configured so thatrotation of the drive shaft 1362 in a first direction creates amechanical linkage between the motor 1360 and a first of the shafts1340/1342, and rotation of the drive shaft 1362 in a second directionthat is opposite the first direction rotates the first of the shafts1340/1342.

The gear system may include a forward-direction primary drive gear 1364that is connected to the drive shaft 1362 and a reverse-directionprimary drive gear 1366 that is connected to the drive shaft 1362. Theforward-direction primary drive gear 1364 and the reverse-directionprimary drive gear 1366 are each ratcheted gears that rotate in responseto rotation of the drive shaft 1362 in the second direction and which donot rotate in response to rotation of the drive shaft 1362 in the firstdirection. The gear system may further include a reversing gear 1368that is configured to engage the reverse-direction primary drive gear1366 and rotate in a direction opposite a direction of rotation of thereverse-direction primary drive gear 1366. The gear system may alsoinclude a plurality of secondary drive members (e.g., the secondarydrive gears 1344) that are mounted on respective ones of the shafts1340/1342, each secondary drive member 1344 mounted so that rotationthereof will result in rotation of a respective one of the shafts1340/1342. The gear system may also include an engagement mechanism(e.g., the cam plate 1370) that is configured to rotate to selectivelyand exclusively engage one or more of the shafts 1340/1342 to move aselected one of the secondary drive members 1344 into engagement withone of the forward-direction primary drive gear 1364 or the reversinggear 1368.

Pursuant to further embodiments of the present invention, methods ofadjusting a phase shifter are provided. These methods may be implementedusing, for example, the multi-RET actuator 1330 of FIGS. 11A-11C.Pursuant to these methods, a drive shaft (e.g., drive shaft 1362) isrotated in a first direction to connect a first of a plurality of gears(e.g., secondary drive gear 1344-1) to a drive mechanism. The driveshaft 1362 is then rotated in a second direction to rotate a gear of thedrive mechanism, wherein rotation of the gear of the drive mechanismcauses rotation of the first of the plurality of gears 1344, androtation of the first of the plurality of gears 1344 mechanicallyadjusts a physical position of a component of the phase shifter.

The plurality of gears may be secondary drive gears 1344 that areconfigured to rotate respective shafts such as worm gear shafts 1340.The drive mechanism may include a forward-direction primary drive gear1364 that is connected to the drive shaft 1362 and a reverse-directionprimary drive gear 1366 that is connected to the drive shaft 1362. Theforward-direction primary drive gear 1364 may be a ratcheted gear thatonly rotates in response to rotation of the drive shaft in a firstdirection, and the reverse-direction primary drive gear 1366 may be aratcheted gear that only rotates in response to rotation of the driveshaft 1362 in the first direction. The plurality of gears may furtherinclude a reversing gear 1368. At least one of the forward-directionprimary drive gear 1364 or the reverse-direction primary drive gear 1366may be configured to engage the first of the plurality of gears 1344-1through the reversing gear 1368.

While FIG. 3 above depicts a conventional wiper-arc type phase shifter,numerous other types of electromechanical phase shifters are known inthe art. It will be appreciated that the actuators disclosed herein aresuitable for use with a wide variety of different phase shifters.

The present invention has been described above with reference to theaccompanying drawings. The invention is not limited to the illustratedembodiments; rather, these embodiments are intended to fully andcompletely disclose the invention to those skilled in this art. In thedrawings, like numbers refer to like elements throughout. Thicknessesand dimensions of some components may be exaggerated for clarity.

Spatially relative terms, such as “under”, “below”, “lower”, “over”,“upper”, “top”, “bottom” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. It will beunderstood that the spatially relative terms are intended to encompassdifferent orientations of the device in use or operation in addition tothe orientation depicted in the figures. For example, if the device inthe figures is turned over, elements described as “under” or “beneath”other elements or features would then be oriented “over” the otherelements or features. Thus, the exemplary term “under” can encompassboth an orientation of over and under. The device may be otherwiseoriented (rotated 90 degrees or at other orientations) and the spatiallyrelative descriptors used herein interpreted accordingly.

Herein, the terms “attached”, “connected”, “interconnected”,“contacting”, “mounted” and the like can mean either direct or indirectattachment or contact between elements, unless stated otherwise.

Well-known functions or constructions may not be described in detail forbrevity and/or clarity. As used herein the expression “and/or” includesany and all combinations of one or more of the associated listed items.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”,“comprising”, “includes” and/or “including” when used in thisspecification, specify the presence of stated features, operations,elements, and/or components, but do not preclude the presence oraddition of one or more other features, operations, elements,components, and/or groups thereof.

That which is claimed is:
 1. An actuator for a plurality of phaseshifters, comprising: a plurality of axially-drivable members, eachaxially-drivable member mounted on a respective parallel shaft, theaxially-drivable members configured to be connected with a respectiveone of the phase shifters; a central drive member; a plurality of rotarymembers, each mounted on a respective one of the parallel shafts;wherein each of the rotary members is axially movable between an engagedposition, in which the rotary member engages the central drive member,and a disengaged position, in which each rotary member is disengagedfrom the central drive member; an engagement mechanism that isconfigured to rotate to selectively and exclusively engage each of theshafts to move a respective rotary member to the engaged position; afirst drive unit to drive the central drive member; and a second driveunit configured to drive the engagement mechanism, wherein theengagement mechanism comprises a cam that engages one of the parallelshafts to move a respective rotary member attached to the shaft to theengaged position.
 2. The actuator defined in claim 1, wherein theaxially-drivable members comprise pistons.
 3. The actuator defined inclaim 1, wherein the parallel shafts comprise worm gear shafts.
 4. Theactuator defined in claim 1, wherein the parallel shafts includespring-loaded shafts that bias the rotary members toward the disengagedposition.
 5. The actuator defined in claim 1, wherein the engagementmechanism includes a ring gear, and wherein the ring gear engages thesecond drive unit.
 6. The actuator defined in claim 1, wherein thecentral drive member is a central drive gear.
 7. The actuator defined inclaim 1, wherein the rotary members are gears.
 8. An actuator for aplurality of phase shifters, comprising: a plurality of axially-drivablemembers, each axially-drivable member mounted on a respective parallelshaft, the axially-drivable members configured to be connected with arespective one of the phase shifters; a central drive gear; a pluralityof gears, each mounted on a respective one of the parallel shafts;wherein each of the gears is axially movable between an engagedposition, in which the gear engages the central drive gear, and adisengaged position, in which each gear is disengaged from the centraldrive gear; an engagement mechanism that is configured to rotate toselectively and exclusively engage each of the shafts to move arespective gear to the engaged position; a first drive motor to drivethe central drive gear; and a second drive motor configured to drive theengagement mechanism, wherein the engagement mechanism includes a ringgear, and wherein the ring gear engages the second drive motor.
 9. Theactuator defined in claim 8, wherein the axially-drivable memberscomprise pistons.
 10. The actuator defined in claim 8, wherein theparallel shafts comprise worm gear shafts.
 11. The actuator defined inclaim 8, wherein the parallel shafts include spring-loaded shafts thatbias the gears toward the disengaged position.
 12. The actuator definedin claim 8, wherein the engagement mechanism comprises a cam thatengages one of the parallel shafts to move a respective gear attached tothe shaft to the engaged position.
 13. An actuator for a plurality ofphase shifters, comprising: a plurality of axially-drivable members,each axially-drivable member mounted on a respective parallel shaft, theaxially-drivable members configured to be connected with a respectiveone of the phase shifters; a central drive gear; a plurality of gears,each mounted on a respective one of the parallel shafts; wherein each ofthe gears is axially movable between an engaged position, in which thegear engages the central drive gear, and a disengaged position, in whicheach gear is disengaged from the central drive gear; a cam plate with acam, the cam plate being configured to rotate such that the camselectively and exclusively engages each of the shafts to move arespective gear to the engaged position; a first drive unit to drive thecentral drive gear; and a second drive unit configured to drive the camplate.
 14. The actuator defined in claim 13, wherein theaxially-drivable members comprise pistons.
 15. The actuator defined inclaim 13, wherein the parallel shafts comprise worm gear shafts.
 16. Theactuator defined in claim 13, wherein the parallel shafts includespring-loaded shafts that bias the gears toward the disengaged position.17. The actuator defined in claim 13, wherein the cam plate includes aring gear, and wherein the ring gear engages the second drive unit.